The present invention relates generally to fluoroelastomer compositions, and more particularly to improved broad temperature capability fluoroelastomer compositions of particular application in hydraulic seals in aircraft and missiles.
Aircraft and missile systems have sealed hydraulic systems which may be subjected to a wide range of environmental conditions and must be capable of storage and operation in very cold environments and of withstanding hot operating temperatures. Hydraulic seals in such systems must therefore perform over a wide temperature range. For example, one missile system has anticipated cold storage requirements of about -65.degree. F. Existing nitrile seals can function at temperatures of about -65.degree. to 275.degree. F. and existing fluoroelastomer seals can function at about 0.degree. to 600.degree. F. However, no existing seal can function satisfactorily near both extremes.
The invention solves or substantially reduces in critical importance problems with existing seal types as suggested above by providing an improved fluoroelastomer seal composition having wide temperature application and excellent low temperature properties. The preferred embodiment of the invention comprises a ternary mixture of a polymer including alternate fluorocarbon and hydrocarbon components joined together, EPDM (a random terpolymer of ethylene, propylene and a diene), and CTFE (an oligomer of chlorotrifluoroethylene) in the approximate ratio of 85:15:10. This composition is compatible with a wide range of hydrocarbon based hydraulic fluids including MIL-H-27601 hydraulic fluid a highly refined paraffin oil commonly used for wide temperature application within military systems.
It is therefore a principal object of the invention to provide an improved fluoroelastomer composition.
It is another object of the invention to provide an improved broad temperature capability fluoroelastomer composition.
It is another object of the invention to provide a fluoroelastomer seal composition having excellent low temperature properties.
It is yet another object of the invention to provide improved broad temperature applicable hydraulic seals of novel fluoroelastomer composition.
These and other objects of the invention will become apparent as the detailed description of representative embodiments proceeds.